This investigation will collect 2 assessments (waves 3-4)on 260 African-American and Latino maltreated siblings for whom we previously obtained 2 assessments one-year apart (waves 1-2) placed in foster care, and who were 7 years old when the study began. Given their substantiated histories of exposure to past familial violence, the sample is high risk for the perpetration of sibling violence, psychological problems, and disruptions in school competence. By working closely with participating child welfare agencies in NYC, biological and foster mothers, we retained 82% of the siblings and completed clinically meaningful analyses of a complex dataset. Preliminary studies indicate that 68% reported moderate to high sibling conflict, 41% showed elevated behavior problems, and 62% met criteria for a child mental disorder. In random regression analyses, sibling conflict, foster caregiving warmth, and less rejecting caregiving made an independent contribution to increased sibling problems. Building on this unique recruited sample, the proposed research objectives are: (1) to examine correlates of sibling violence, namely, past familial victimization (exposure to child neglect, abuse, and/or intimate partner violence), child mental disorder (particularly disruptive behavior disorders), and placement variables (together or apart; and foster home instability) over time; (2) to examine the contribution of sibling violence on increased psychological symptoms (increased internalizing, externalizing) and disruptions in school competence, over time; and (3) to evaluate the moderating role of sibling positivity, foster caregiving quality, and differential warmth and responsive management in the linkage between sibling violence and increased symptoms and disruptions in school competence, over time. The identification of modifiable risk and protective factors in the social ecology of foster care is a crucial first step in effective prevention of sibling violence in foster children.